-
A current limiter circuit limits the current supplied by the generator. As the excitation current is limited, the mechanical power that the drive part supplies is also limited.

 -If the protection circuits detect a fault, the generator excitation is cut off: . electronically by shorting to ground the Voltage Regulation Shut Down: (VR S/D Down), . by cutting off its supply by the GCR.
 -With a generator selected by the GEN pushbutton switch, the excitation command signal (VR S/D Line) is used to command: . the initial generator excitation at engine start, . its de-energization at engine shutdown. (325 Hz line frequency).
R (2) Not Applicable
R (3) Not Applicable
R (4) Generator control and protection functions These functions are mainly the generator excitation and line contactor control. The excitation is controlled via the GCR. The line contactor is controlled via the Power Ready Relay (PR) which is energized when:
 -
the speed is more than 4730 rpm and,

 -
the GCR is closed.
 Signals received or generated by the GCU control these two relays.

 The following control or fault signals cause generator shutdown or
 de-energization:
 (Ref. Fig. 004)

 -IDG disconnection,
 -GLC failure (BTC is only locked out),
R 1EFF : 001-049, 051-099, 101-149, 151-199, 1 24-22-00Page 25 1201-299, 301-399, 1Aug 01/05 1 1 1CES 1

 Zone of Protection
 Figure 004

R 1EFF : 001-049, 051-099, 101-149, 151-199, 1 24-22-00Page 26 1201-299, 301-399, 1Aug 01/05 1 1 1CES 1

 -engine shutdown with the ENG FIRE pushbutton switches (IDG position),
 -PMG short circuit,
 - over/under voltage,
 - over/under frequency,
 - open cable (IDG position),

 -APU ready (APU position),
 -differential protection: . Zone 1 : monitoring of the generator 1 or 2 and feeders, . Zone 2 : monitoring between the line contactor and the primary circuit breakers related to the channel. Monitoring between the BTC of the applicable channel and the primary circuit breakers,
 -GEN pushbutton switch,
 -short circuit of the rotating diodes,
 -phase sequence (in this case, the GCU opens the PR relay only). Except in some particular cases, the system may be reset by setting the GEN pushbutton switch to OFF.
 The PR is also controlled by the IDG drive underspeed. This prevents the generator from being energized.
 NOTE : Each time the generator is de-energized because of a fault
____ signal, do a GCU reset. To do this, push (ON) then release (OFF) the related GEN pushbutton switch.
 NOTE : After:
____
 -
activation of a differential pressure, or

 -
activation of a GLC fault.
 The system can be reset only two times via the GEN pushbutton
 switch.

 A table listing all these functions is shown below. GCU DETECTION:
 ------------------------------------------------------------------------------| FUNCTION |SENSING | THRESHOLD |TIME DELAY |TRIPS| REMARKS |INHIBITION| |-----------|--------|-----------|-----------|-----|---------------|----------| |Overvoltage|Highest | 130 VAC, | Inverse | GLC | Turns off | | |(OV) |phase at| + or -|(compatible| GCR | voltage | | | |POR | 1.5 V | with the | | regulator | | |(IDG and | | | guaranteed| | | | | APU GEN) | | | transient | | | | | | | | voltage | | | | | | | | to the | | | | | | | | network) | | | | |-----------|--------|-----------|-----------|-----|---------------|----------| | Undervol- | Lowest | 100 VAC, |4 s to 5 s | GLC | Turns off | |
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 ------------------------------------------------------------------------------
| FUNCTION |SENSING | THRESHOLD |TIME DELAY |TRIPS| REMARKS |INHIBITION| |-----------|--------|-----------|-----------|-----|---------------|----------| | tage (UV) | phase | + or -| | GCR | voltage | | | | at POR | 4 V | | | regulator | | | | voltage| | | | | | | (IDG and | | | | | |Locked out| | APU GEN) | | | | | |by US TRIP| | | | | | | |APU TRIP | | | | | | | |or UP TRIP| |-----------|--------|-----------|-----------|-----|---------------|----------| | Overfre-| PMG | PMG fre-|3 s to 5 s | GLC | Turns off | | | quency(OF)| fre-| quency | | GCR | voltage | | | (IDG and | quency | correspon-| | | regulator | | | APU GEN) | | ding to | | | | | | | | (433 Hz | | | | | | | | + or -| | | | | | | | 3 Hz) | | | | | |-----------|--------|-----------|-----------|-----|---------------|----------| | Underfre- | PMG | PMG fre-|3 s to 5 s | GLC | Turns off |Locked out| | quency(UF)| fre-| quency | | GCR | voltage |by US TRIP| | (IDG and | quency | correspon-| | | regulator | or | | APU GEN) | | ding to | | | |APU TRIP | | | | (363 Hz | | | | | | | | + or -| | | | | | | | 3 Hz) | | | | | |-----------|--------|-----------|-----------|-----|---------------|----------| | Underspeed| IDG |4730 RPM |100 ms max.| GLC | Generator | | | (US) | input | + or -| | | excitation | | | (IDG) | speed | 30 RPM | | | is cut off | | | |magnetic| | | | through an UF | | | | pick-up| | | | signal at | | | | | | | | frequency | | | | | | | | below 325 Hz | | |-----------|--------|-----------|-----------|-----|---------------|----------| | Overload | Average| 277 A | 13 s | | Signal for | | | (OL) | of the | + or -| + or -| | warning and | | | (IDG and | three | 13 A | 3 s | | automatic gal-| | | APU GEN) | genera-| | | | ley shedding | | | | tor | | | | of APU GEN on | | | | current| | | | ground | | |-----------|--------|-----------|-----------|-----|---------------|----------| | Phase se- |2 phases| A.B.C.N. | None | GLC | Prevents GLC | | | quence(PS)|at POR | phase | | | closure if | | | | | sequence | | | phase sequence| | | (IDG and | | | | | is not ABCN | | | APU GEN) | | | | | | |
　
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